1. Field of the Invention
The present invention relates to liquid crystal panels (also referred to as “liquid crystal display panels”), methods of fabricating the same, and apparatuses used to fabricate the same. Furthermore, the present invention relates to apparatuses used to stick a polarizing plate and particularly to apparatuses used in a liquid crystal panel fabrication process to stick a polarizing plate that is supplied in a roll.
2. Description of the Background Art
In general a liquid crystal panel has a structure formed of two glass substrates stacked one on the other in parallel and stuck together with a predetermined small gap posed therebetween and filled with liquid crystal. As a method of fabricating such a crystal panel, a conventional, general method will be described with reference to FIGS. 44–49. As shown in FIG. 44, when a thin film transistor (TFT) glass substrate 101 and a color filter (CF) glass substrate 102 are to be stuck together, a sealing agent 103 is arranged on one of the substrates. In the FIG. 44 example, TFT glass substrate 101 has a surface with sealing agent 103 adhesively fixed thereon. Sealing agent 103 is arranged in a frame to define a region to serve as a space confining liquid crystal (hereinafter referred to as a “liquid crystal cell”). It is, however, not completely closed. As shown in FIG. 44, it has an opening to serve as an inlet 116. TFT and CF glass substrates 101 and 102 are substrates having a large size allowing a plurality of crystal panels to be provided therefrom, and on the substrate a plurality of sealing agents 103 are arranged. Sealing agent 103 is thermosetting resin or the like.
TFT and CF glass substrates 101 and 102 are stuck together by sealing agent 103 and heated to allow sealing agent 103 to set to provide a large format substrate formed of the stuck substrates. TFT and CF glass substrates 101 and 102 are then divided for each individual region surrounded by sealing agent 103. Thus, as shown in FIG. 45, a substrate formed of substrates stuck together 114 and including a liquid crystal cell 115 is obtained. The substrate formed of substrates stuck together 114 is accommodated in a vacuum apparatus and liquid crystal cell 115 has its interior and exterior both vacuumed. Then, as shown in FIG. 46, inlet 116 defined by an opening of sealing agent 103 is immersed in liquid crystal 104 and the vacuum apparatus's internal atmosphere is gradually returned to atmospheric pressure. By a difference in pressure between the interior and exterior of liquid crystal cell 115, and capillarity, liquid crystal 104 is introduced into liquid crystal cell 115. Liquid crystal cell 115 is thus filled with liquid crystal 104. Subsequently, sealing resin 105, ultraviolet ray curing resin, is applied to inlet 116. Ultraviolet radiation is provided to illuminate sealing resin 105 to allow it to set to seal liquid crystal 104 in liquid crystal cell 115 to obtain the substrate formed of substrates stuck together 114, as shown in FIG. 47.
The substrate formed of substrates stuck together 114 is structured for example to have one side with a terminal portion (not shown) exposed. To this terminal portion a probe pin is connected, and an inspection is conducted. If the inspection does not reveal any abnormality, a polarizing plate 106 supplied in a sheet in a size corresponding to the substrate formed of substrates stuck together 114 is stuck on one or opposite sides of panel 114, as shown in FIG. 48. A liquid crystal panel 140 is thus obtained.
The conventional liquid crystal panel fabrication method is represented in a flow chart, as shown in FIG. 49. In FIG. 49, at the step of sticking a polarizing plate a liquid crystal panel is completed. Note that FIG. 49 also shows a process performed after the liquid crystal panel is completed. More specifically, by connecting a flexible printed circuit (FPC) to a terminal portion of the liquid crystal panel and attaching a backlight and a case, a liquid crystal display device is obtained.
However, the polarizing plate must be stuck slowly to prevent generation of static electricity. For example, sticking a single plate requires a time of approximately 8 to 10 seconds. In particular, a small size liquid crystal panel used for example in mobile phones is produced by dividing a single, large format glass substrate to provide several hundreds of liquid crystal panels. In that case, such a conventional art as described above requires a significantly increased number of operations in the steps for example of sticking the polarizing plate, conducting an inspection, and the like, which is significantly time consuming.
This disadvantage may be addressed, as disclosed in Japanese Patent Laying-Open No. 6-342139, by sticking a polarizing plate on an elongate substrate provided with regions arranged in a row to serve as cells, and then dividing the same for each cell. This method does provide a reduced cycle time for the step of sticking the polarizing plate (a reduced time required for the step of sticking the polarizing plate for a single liquid crystal panel). In recent years, however, a single large format glass substrate has also been used to produce several hundreds of liquid crystal panels, and in such a case the method employing the elongate substrate as described above does not provide a cycle time sufficiently effectively reduced.
Conventionally when a glass substrate of large size is used to produce liquid crystal panels of medium or small size the glass substrate has been divided into small pieces to form discrete cells and a polarizing plate has been stuck on each cell. This approach, however, requires sticking a polarizing plate on each single cell and also when the influence of static electricity is considered the apparatus cannot simply be rapidly operated. As such, to stick a single polarizing plate on one side of the cell, a time of approximately eight to ten seconds would be required. In addition, the substrate having been divided provides a large number of cells and a large number of apparatuses is accordingly required. As such it is desirable that in a condition with as many as cells included, collectively a polarizing plate is stuck thereon and then divided to achieve a significantly reduced cycle time of the step of sticking the polarizing plate.
More specifically, it is significantly effective if a collective polarizing plate can be stuck for example on a glass substrate divided in an elongate geometry to facilitate the step of introducing liquid crystal, a large size substrate formed by introducing liquid crystal in droplets and sticking substrates together, or a similar substrate. For example from a glass substrate having a side of 600 to 700 mm no less than 200 cells can be obtained, and when a polarizing plate is stuck on the glass substrate having a side of 600 to 700 mm it can be stuck thereon with efficiency increased by approximately double digits dramatically. Normally, a polarizing plate to be stuck on cells is previously cut in a form matching a single cell, and thereafter undergoes an inspection, one by one. As such the component costs significantly. If a polarizing plate supplied in a roll can be stuck on cells, not only can an inspection of discrete cells be eliminated but the dust that is caused when a substrate is cut into pieces can also be prevented.
Conventionally a rolled polarizing plate has been stuck on a glass substrate for example as disclosed in Japanese Patent Laying-Open No. 60-192914. Furthermore, an elongate polarizing plate has been stuck on a glass substrate by a method for example as disclosed in Japanese Patent Laying-Open No. 1-260417.
Japanese Patent Laying-Open No. 60-192914 discloses that a rolled polarizing plate is unrolled and a liquid crystal display panel is stuck directly thereon and subsequently the polarizing plate is cut. With this method, however, the polarizing plate has a large portion wasted. Furthermore, a portion unnecessary as a liquid crystal panel would also have a polarizing plate stuck thereon, which renders it difficult to perform a subsequent division step. To produce a transmission liquid crystal display device, in particular, it is necessary that a liquid crystal panel has opposite sides with a polarizing plate stuck thereon. The axes of polarization are orthogonal to each other and if the polarizing plate is large a marker (a reference for a division step to provide cells) provided in a glass substrate cannot be read.
Furthermore in such a configuration as disclosed in Japanese Patent Laying-Open No. 1-260417 if the substrate and the polarizing plate are of large size a pneumatic chuck mechanism moving the elongate polarizing plate and a press for half-cutting are spaced wide apart and consequently the apparatus itself would have a significantly increased size disadvantageously.
Furthermore, the apparatus described in Japanese Patent Laying-Open No. 1-260417 cuts a polarizing plate first in a strip and then in a size in accordance with a liquid crystal display device. The polarizing plate needs to be cut twice and the apparatus is accordingly required to have an increased size disadvantageously.